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Discussion Starter · #1 ·
I have a piece of equipment with factory openings for conduit, and the manufacturer's manual specifies not to enlarge these openings.

Unfortunately, only 3/4" trade size factory openings are available in the location I need. The output wiring requires 1" RMC. Most of my conduit run, will be 1" RMC. My question is, how can I make the local connection to the enclosure?

I have (4) #6 thwn-2 and (1) # 10 thwn-2 ground. This fits in 1" RMC no trouble, but not in 3/4" RMC. It is a pinch beyond the 40% maximum for 3/4" RMC. It does fit, barely, in 3/4" IMC, at 38% fill.

Searching supply sites, I see that IMC and RMC have the same set of fittings. If this is indeed the case, are fittings for RMC and IMC both built with the same inside clearance as IMC straight sections have?

Fittings such as short nipples and Myers hubs.

This piece of equipment would likely be on the feed side of the wire pull, so due to the low tension, I'm not concerned with choking the wire thru 38% fill.
 

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I have a piece of equipment with factory openings for conduit, and the manufacturer's manual specifies not to enlarge these openings.

Unfortunately, only 3/4" trade size factory openings are available in the location I need. The output wiring requires 1" RMC. Most of my conduit run, will be 1" RMC. My question is, how can I make the local connection to the enclosure?

I have (4) #6 thwn-2 and (1) # 10 thwn-2 ground. This fits in 1" RMC no trouble, but not in 3/4" RMC. It is a pinch beyond the 40% maximum for 3/4" RMC. It does fit, barely, in 3/4" IMC, at 38% fill.

Searching supply sites, I see that IMC and RMC have the same set of fittings. If this is indeed the case, are fittings for RMC and IMC both built with the same inside clearance as IMC straight sections have?

Fittings such as short nipples and Myers hubs.

This piece of equipment would likely be on the feed side of the wire pull, so due to the low tension, I'm not concerned with choking the wire thru 38% fill.
...if they are not threaded hubs at the factory equipment openings, I would just enlarge the holes to accommodate the 1"
 

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Discussion Starter · #4 · (Edited)
...if they are not threaded hubs at the factory equipment openings, I would just enlarge the holes to accommodate the 1"
They are not threaded hubs. I believe it is powder coated sheet metal, similar to most NEMA3R disconnect enclosures, but I cannot tell for sure.

I think the manufacturer wrote that blurb in the manual as a way of pleading ignorance and transferring liability. They say it is UL Listed the way that it comes, and that contractors making the knockouts would void the listing. Hence the factory knockouts.

I cannot fathom how they thought that 3/4" would be a common size. Not sure why they didn't just use concentric ring knockouts.

I don't even think the contractor will even notice it, or even think twice about enlarging the openings, since the manual is often the first thing in the circular file.
 

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Discussion Starter · #5 ·
The od of Rigid is the same as IMC. the ID of IMC is slightly larger.
I would use a C condulet or a junction box to get me pipe next to the machine and nipple them together.

Ahh, I see. That allows me to take advantage of the local pull 60% rule.

My original question was whether or not the ID of fittings that are dual-rated for use with IMC and RMC, is the same as the ID of IMC. That would allow me to omit the pull box.
 

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Run 1" up to the machine.. Then install a union, reducer and close nipple. I think it would look better than a coupling, reducer and nipple..
 

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Conduit bodies of the same trade size as the conduit are permitted the same wire fill as the conduit itself as long as none of the conductors are larger than #6.
314.16(C) Conduit Bodies.
(1) General. Conduit bodies enclosing 6 AWG conductors or smaller, other than short-radius conduit bodies as described in 314.16(C)(3), shall have a cross-sectional area not less than twice the cross-sectional area of the largest conduit or tubing to which they can be attached. The maximum number of conductors permitted shall be the maximum number permitted by Table 1 of Chapter 9 for the conduit or tubing to which it is attached.
 

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Do you need the 10 equipment grounding conductor- It can be eliminated unless it is speced. Personally I think I would enlarge the hole with a ko punch
 

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Put a disconnect and run IMC 3/4" as it is .235 sq.in. It calculates .2394 sq.in but I don't you would get call on it.

Or you can changes from rigid the last inch to IMC.
 
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